Polyvinyl alcohol-based fiber membranes with high strength and ultraviolet shielding properties for enhancing the shelf life of grapes

Currently, the rising environmental concerns caused by nonbiodegradable food packaging materials have promoted the research and development of biodegradable alternatives. Polyvinyl alcohol (PVA) was selected as the substrate, and zinc oxide nanoparticles (ZnONPs) and titanium dioxide nanoparticles (TiO₂NPs) were blended and modified with PVA, respectively. Based on the electrostatic spinning technology to prepare fiber membranes with high strength and UV blocking properties for grapes preservation. The study indicated that the tensile strength of PVA fiber membranes increased by 243% and 209% when ZnONPs and TiO₂NPs were added at 1%, respectively. Under UV radiation, the PVA/ZnO composite membranes exhibited superior UV absorption than the PVA/TiO₂ composite membranes. After conducting TG tests, it was found that the addition of ZnONPs decreased the thermal stability of the fiber membranes, while TiO₂NPs could improve the thermal stability. Both composite membranes could extend grapes' shelf life, but the PVA/ZnO composite membranes were more effective at maintaining freshness than the PVA/TiO₂ composite membranes.     

On the Efficacy of ZnO Nanostructures against SARS-CoV-2

In 2019, the new coronavirus disease (COVID-19), related to the severe acute respiratory syndrome coronavirus (SARS-CoV-2), started spreading around the word, giving rise to the world pandemic we are still facing. Since then, many strategies for the prevention and control of COVID-19 have been studied and implemented. In addition to pharmacological treatments and vaccines, it is mandatory to ensure the cleaning and disinfection of the skin and inanimate surfaces, especially in those contexts where the contagion could spread quickly, such as hospitals and clinical laboratories, schools, transport, and public places in general. Here, we report the efficacy of ZnO nanoparticles (ZnONPs) against SARS-CoV-2. NPs were produced using an ecofriendly method and fully characterized; their antiviral activity was tested in vitro against SARS-CoV-2, showing a decrease in viral load between 70% and 90%, as a function of the material’s composition. Application of these nano-antimicrobials as coatings for commonly touched surfaces is envisaged.     

Earthworm coelomocytes as nanoscavenger of ZnO NPs

Earthworms can ‘biotransform’ or ‘biodegrade’ chemical contaminants, rendering them harmless in their bodies, and can bioaccumulate them in their tissues. They ‘absorb’ the dissolved chemicals through their moist ‘body wall’ due to the interstitial water and also ingest by ‘mouth’ while soil passes through the gut. Since the advent of the nanotechnology era, the environmental sink has been continuously receiving engineered nanomaterials as well as their derivatives. Our current understanding of the potential impact of nanomaterials and their natural scavenger is limited. In the present investigation, we studied the cellular uptake of ZnO nanoparticles (NPs) by coelomocytes especially by chloragocytes of Eisenia fetida and their role as nanoscavenger. Results from exposure to 100- and 50-nm ZnO NPs indicate that coelomocytes of the earthworm E. fetida show no significant DNA damage at a dose lower than 3 mg/l and have the potential ability to uptake ZnO NPs from the soil ecosystem and transform them into microparticles.     

Comparison Study of Cytotoxicity of Bare and Functionalized Zinc Oxide Nanoparticles

In this paper, a study of the cytotoxicity of bare and functionalized zinc oxide nanoparticles (ZnO NPs) is presented. The functionalized ZnO NPs were obtained by various types of biological methods including microbiological (intra- and extracellular with Lactobacillus paracasei strain), phytochemical (Medicago sativa plant extract) and biochemical (ovalbumin from egg white protein) synthesis. As a control, the bare ZnO NPs gained by chemical synthesis (commercially available) were tested. The cytotoxicity was measured through the use of (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) dye as well as lactate dehydrogenase (LDH) assays against murine fibroblast L929 and Caco-2 cell lines. As a complementary method, scanning electron microscopy (SEM) was performed to assess the morphology of the tested cells after treatment with ZnO NPs. The microscopic data confirmed the occurrence of apoptotic blebbing and loss of membrane permeability after the administration of all ZnO NPs. The reactive oxygen species (ROS) concentration during the cell lines’ exposure to ZnO NPs was measured fluorometrically. Additionally, the photocatalytic degradation of methylene blue (MB) dye in the different light conditions, as well as the antioxidant activity of bare and functionalized ZnO NPs, is also reported. The addition of all types of tested ZnO NPs to methylene blue resulted in enhanced rates of photo-degradation in the presence of both types of irradiation, but the application of UV light resulted in higher photocatalytic activity of ZnO NPs. Furthermore, bare (chemically synthetized) NPs have been recognized as the strongest photocatalysts. In the context of the obtained results, a mechanism underlying the toxicity of bio-ZnO NPs, including (a) the generation of reactive oxygen species and (b) the induction of apoptosis, is proposed.     

Influence of zinc oxide nanoparticles on the crystallization behavior of electrospun poly(3-hydroxybutyrate-co-3-hydroxyvalerate) nanofibers

Pure poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and zinc oxide (ZnO)/PHBV composite nanofibers were fabricated by an electrospinning method. ZnO nanoparticles (NPs) with a diameter of about 10-20 nm were doped in the PHBV fibers and no dispersion agent was utilized. Both pure PHBV and composite electrospun fibers were smooth and uniform. ZnO NPs did not affect the basic crystalline structure of electrospun PHBV fibers. The well dispersion of NPs was attributed to the interaction of hydrogen bonds between -OH groups on the surface of ZnO and CO groups in the PHBV. ZnO NPs were not nucleating or modifying agents but retarding agents for crystallization in the polymer matrix. The crystallinity and crystallization rate was lowered by adding ZnO NPs. The well dispersion of ZnO NPs in the electrospun nanofibers was confirmed by TEM characterization. A hypothesis was developed to interpret the influence of ZnO NPs on the crystalline behavior of electrospun PHBV fibers.     

Detection of trivalent-iron based on low-dimensional semiconductor metal oxide nanostructures for environmental remediation by ICP-OES technique

A large-scale synthesis of undoped low-dimensional semiconductor metal oxide nanostructures (ZnO nanoparticles, NPs) by simple wet-chemical method was performed using reducing agents at low temperature. The NPs were characterized in terms of their morphological, structural, and optical properties, and efficiently applied for the metal ions uptake. The detailed structural, compositional, and optical characterizations of the NPs were evaluated by powder X-ray diffraction pattern (XRD), Fourier-transform infra-red spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Electron dispersion spectroscopy (EDS), and UV–vis. spectroscopy, respectively which confirmed that the obtained NPs are well-crystalline undoped ZnO and possessed good optical properties. The ZnO NSs morphology was investigated by FESEM, which confirmed that the calcined materials were spherical shape in nano-level and growth in huge-quantity. The analytical efficiency of newly synthesized ZnO NPs was also investigated for a selective separation of trivalent iron [Fe(III)] prior to its determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). The selectivity of ZnO NPs towards different metal ions, including Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Ni(II), Zn(II), and Zr(IV), was studied. Data obtained from the selectivity study suggested that that ZnO NPs phase was the most selective towards Fe(III). The static uptake capacity of Fe(III) was found to be ~79.80 mg g⁻¹. Moreover, adsorption isotherm data also provided that the adsorption process was mainly monolayer on a homogeneous adsorbent surface.     

Morphological and Proteomic Analyses of Soybean Seedling Interaction Mechanism Affected by Fiber Crosslinked with Zinc-Oxide Nanoparticles

Nanoparticles (NPs) enhance soybean growth; however, their precise mechanism is not clearly understood. To develop a more effective method using NPs for the enhancement of soybean growth, fiber crosslinked with zinc oxide (ZnO) NPs was prepared. The solution of ZnO NPs with 200 nm promoted soybean growth at the concentration of 10 ppm, while fibers crosslinked with ZnO NPs promoted growth at a 1 ppm concentration. Soybeans grown on fiber cross-linked with ZnO NPs had higher Zn content in their roots than those grown in ZnO NPs solution. To study the positive mechanism of fiber crosslinked with ZnO NPs on soybean growth, a proteomic technique was used. Proteins categorized in photosynthesis and secondary metabolism accumulated more in soybeans grown on fiber crosslinked with ZnO NPs than in those grown in ZnO NPs solution. Furthermore, significantly accumulated proteins, which were NADPH oxidoreductase and tubulins, were confirmed using immunoblot analysis. The abundance of NADPH oxidoreductase increased in soybean by ZnO NPs application. These results suggest that fiber crosslinked with ZnO NPs enhances soybean growth through the increase of photosynthesis and secondary metabolism. Additionally, the accumulation of NADPH oxidoreductase might relate to the effect of auxin with fiber crosslinked with ZnO NPs on soybean growth.     

Novel synthesis of ZnO nanoparticles and their enhanced anticancer activity: Role of ZnO as a drug carrier

In this work, a simple and versatile technique was developed to prepare highly crystalline ZnO nanoparticles (ZnO NPs) by organic precursor method using 5, 6 dimethyl benzimidazole and Zn(CH₃COO)₂·2H₂O followed by calcination. These synthesized ZnO NPs were used as a drug carrier to form 5-Fluorouracil (5 Fu) encapsulated ZnO NPs by varying the molar ratio (100–300:1) of ZnO NPs to 5-Fu. X-ray diffraction (XRD) results indicated that the ZnO NPs had single phase nature with the wurtzite structure. Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) results showed nanometer dimension of the NPs. FTIR analysis further reaffirmed the formation/encapsulation of ZnO NPs. UV–vis spectroscopy determined the encapsulation efficiency (EE) and loading capacity (LC) of 5-Fu drug on ZnO NPs. HPLC analysis of encapsulated NPs indicated release of 5-Fu was higher at tumor cell pH (pH 6.0) than physiological pH. Moreover, the anti-tumor activity of ZnO NPs and 5-Fu-encapsulated ZnO NPs investigated using flow cytometry demonstrated that 5-Fu encapsulated ZnO NPs have more anti-tumor activities than 5-Fu itself toward MCF-7 (Breast cancer) cell line. Also, cytotoxicity of MCF-7 increased with the increase of ZnO NPs: 5-Fu ratio. This research will introduce a new concept to synthesize 5-fluorouracil encapsulated ZnO NPs and its application towards the cancer cell line. Thus, the ZnO NPs could not only apply as the drug carrier to deliver 5-Fluorouracil into the cancer cells, but also enhances anti-tumor activity.     

In vitro anticancer activity and comparative green synthesis of ZnO/Ag nanoparticles by moringa oleifera,mentha piperita,and citrus lemon

This study proposes a simple, effective, and environmentally friendly approach for the synthesis of zinc oxide/silver nanoparticles (ZnO/Ag NPs) using three different plant extracts. The plants used in this study were moringa oleifera (MO), mentha piperita (MP), and citrus lemon (CL). Characterizations of ZnO/Ag NPs were done using ultraviolet–visible spectroscopy (UV vis), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) along with energy dispersive spectroscopy (EDX), and fourier transform infrared spectroscopy (FTIR). In accordance with size distribution findings, ZnO/Ag NPs synthesized with MO have a narrow size distribution, with the average particle size being 119 ± 36 nm. Among these three reducing agent MO act as the best reducing agent. Moreover, the anticancer activity of silver nanoparticles (Ag NPs), zinc oxide nanoparticles (ZnO NPs) and ZnO/Ag NPs synthesized with MO were demonstrated in human cervical cancer cells (HeLA). The results revealed that ZnO/Ag NPs demonstrate in vitro cell viability of 72%, 81%, and 84% using 2.5, 5, and 10 μgml^?1of ZnO/Ag NPs for 24 h. While Ag NPs and ZnO NPs prepared with MO showed 50% and 60% cell viability using 2.5 μgml^?1concentration for 24 h. This showed that the ZnO/Ag NPs act as a strong anticancer agent compared to Ag NPs and ZnO NPs. Overall, this research proposes a green synthesis approach for ZnO/Ag NPs with a wide range of potential uses, particularly in biomedicine.     

Biogenic synthesis and characterization of gold nanoparticles by Escherichia coli K12 and its heterogeneous catalysis in degradation of 4-nitrophenol

Room-temperature extracellular biosynthesis of gold nanoparticles (Au NPs) was achieved using Escherichia coli K12 cells without the addition of growth media, pH adjustments or inclusion of electron donors/stabilizing agents. The resulting nanoparticles were analysed by ultraviolet–visible (UV–vis) spectrophotometry, atomic force microscopy, transmission electron microscopy and X-ray diffraction. Highly dispersed gold nanoplates were achieved in the order of around 50 nm. Further, the underlying mechanism was found to be controlled by certain extracellular membrane-bound proteins, which was confirmed by Fourier transformation-infrared spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis. We observed that certain membrane-bound peptides are responsible for reduction and subsequent stabilization of Au NPs (confirmed by zeta potential analysis). Upon de-activation of these proteins, no nanoparticle formation was observed. Also, we prepared a novel biocatalyst with Au NPs attached to the membrane-bound fraction of E. coli K12 cells serving as an efficient heterogeneous catalyst in complete reduction of 4-nitrophenol in the presence of NaBH₄ which was studied with UV–vis spectroscopy. This is the first report on bacterial membrane-Au NP nanobiocomposite serving as an efficient heterogeneous catalyst in complete reduction of nitroaromatic pollutant in water.     

Antidiabetic Activity of Zinc Oxide and Silver Nanoparticles on Streptozotocin-Induced Diabetic Rats

The use of nanoparticles in medicine is an attractive proposition. In the present study, zinc oxide and silver nanoparticles were evaluated for their antidiabetic activity. Fifty male albino rats with weight 120 ± 20 and age 6 months were used. Animals were grouped as follows: control; did not receive any type of treatment, diabetic; received a single intraperitoneal dose of streptozotocin (100 mg/kg), diabetic + zinc oxide nanoparticles (ZnONPs), received single daily oral dose of 10 mg/kg ZnONPs in suspension, diabetic + silver nanoparticles (SNPs); received a single daily oral dose of SNP of 10 mg/kg in suspension and diabetic + insulin; received a single subcutaneous dose of 0.6 units/50 g body weight. Zinc oxide and silver nanoparticles induce a significant reduced blood glucose, higher serum insulin, higher glucokinase activity higher expression level of insulin, insulin receptor, GLUT-2 and glucokinase genes in diabetic rats treated with zinc oxide, silver nanoparticles and insulin. In conclusion, zinc oxide and sliver nanoparticles act as potent antidiabetic agents.     

Gas sensing properties of conducting polymer/Au-loaded ZnO nanoparticle composite materials at room temperature

In this work, a new poly (3-hexylthiophene):1.00 mol% Au-loaded zinc oxide nanoparticles (P3HT:Au/ZnO NPs) hybrid sensor is developed and systematically studied for ammonia sensing applications. The 1.00 mol% Au/ZnO NPs were synthesized by a one-step flame spray pyrolysis (FSP) process and mixed with P3HT at different mixing ratios (1:1, 2:1, 3:1, 4:1, and 1:2) before drop casting on an Al₂O₃ substrate with interdigitated gold electrodes to form thick film sensors. Particle characterizations by X-ray diffraction (XRD), nitrogen adsorption analysis, and high-resolution transmission electron microscopy (HR-TEM) showed highly crystalline ZnO nanoparticles (5 to 15 nm) loaded with ultrafine Au nanoparticles (1 to 2 nm). Film characterizations by XRD, field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray (EDX) spectroscopy, and atomic force microscopy (AFM) revealed the presence of P3HT/ZnO mixed phases and porous nanoparticle structures in the composite thick film. The gas sensing properties of P3HT:1.00 mol% Au/ZnO NPs composite sensors were studied for reducing and oxidizing gases (NH₃, C₂H₅OH, CO, H₂S, NO₂, and H₂O) at room temperature. It was found that the composite film with 4:1 of P3HT:1.00 mol% Au/ZnO NPs exhibited the best NH₃ sensing performances with high response (approximately 32 to 1,000 ppm of NH₃), fast response time (4.2 s), and high selectivity at room temperature. Plausible mechanisms explaining the enhanced NH₃ response by composite films were discussed.     

Neuroinflammation is induced by tongue-instilled ZnO nanoparticles via the Ca<Superscript>2+</Superscript>-dependent NF-κB and MAPK pathways

Background

The extensive biological applications of zinc oxide nanoparticles (ZnO NPs) in stomatology have created serious concerns about their biotoxicity. In our previous study, ZnO NPs were confirmed to transfer to the central nervous system (CNS) via the taste nerve pathway and cause neurodegeneration after 30 days of tongue instillation. However, the potential adverse effects on the brain caused by tongue-instilled ZnO NPs are not fully known.

Methods

In this study, the biodistribution of Zn, cerebral histopathology and inflammatory responses were analysed after 30 days of ZnO NPs tongue instillation. Moreover, the molecular mechanisms underlying neuroinflammation in vivo were further elucidated by treating BV2 and PC12 cells with ZnO NPs in vitro.

Results

This analysis indicated that ZnO NPs can transfer into the CNS, activate glial cells and cause neuroinflammation after tongue instillation. Furthermore, exposure to ZnO NPs led to a reduction in cell viability and induction of inflammatory response and calcium influx in BV2 and PC12 cells. The mechanism underlying how ZnO NPs induce neuroinflammation via the Ca²⁺-dependent NF-κB, ERK and p38 activation pathways was verified at the cytological level.

Conclusion

This study provided a new way how NPs, such as ZnO NPs, induce neuroinflammation via the taste nerve translocation pathway, a new mechanism for ZnO NPs-induced neuroinflammation and a new direction for nanomaterial toxicity analysis.

     

Effect of zinc precursor ratio on morphology and luminescent properties of ZnO nanoparticles synthesized in CTAB medium

In this study, the effect of zinc precursor ratio on structural, morphology and luminescent properties of zinc oxide (ZnO) nanoparticles (NPs) prepared by cationic surfactant-assisted method was studied. ZnO NPs were prepared at room temperature by increasing Zn²⁺: CTAB mole ratio. The pristine ZnO samples showed phase-purity (without need for calcination) as shown by X-ray diffractograms (XRD). Nitrogen adsorption ? desorption analysis showed that the samples exhibit Type III isotherm and H3 hysteresis with mesoporosity. The triangular- to quadrilateral-shaped morphological evolution of the ZnO NPs with increasing concentrations of zinc ions was confirmed by SEM and TEM images of the samples. The UV–Vis–DRS studies showed blue-shifted λ_max (band gap) in all the ZnO samples which indicated their nanostructured nature. The photoluminescence spectra of these ZnO samples show emissions in UV and visible regions. The mechanism of formation of nanostructured ZnO was suggested based on the model reported for mesoporous silica synthesized in CTAB medium.     

Visible to near-infrared light harvesting in Ag2S nanoparticles/ZnO nanowire array photoanodes

Pronounced absorption in the visible-NIR range of 400-1300 nm is demonstrated in the Ag(2)S nanoparticles (NPs)/ZnO nanowire (NW) array. ZnO NW arrays are grown on indium tin oxide substrates using chemical bath deposition. The Ag(2)S NPs are sequentially formed on the ZnO NWs through sonochemical synthesis. Structural characterizations indicate the slight deconstruction of surface of ZnO NWs during Ag(2)S NPs formation. By employing polysulfide electrolyte, short-circuit current (J(sc)), open-circuit voltage and therefore the efficiency of the Ag(2)S NP-sensitized ZnO NW solar cell are improved with increasing the initial sulfur concentration in the sulfur-polysulfide electrolyte. The Ag(2)S NP-sensitized ZnO NW solar cell shows a conversion efficiency of 0.49% with a superior J(sc) of ~13.7 mA cm(-2) under AM 1.5 illumination at 100 mW cm(-2). Incident photon conversion efficiency measurements reveal that Ag(2)S NPs contribute to 33.4% and 65.2% of J(sc) in the wavelength ranges of 400-700 nm and 700-1300 nm, respectively.     

Characterization of multifunctional PAN/ZnO nanofibrous composite filter for fine dust capture and photocatalytic activity

The multifunctional air filter, which can provide low resistance to airflow, was prepared from polyacrylonitrile (PAN) nanofibers (NFs) by impregnating zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activity. Incorporation of ZnO NPs improved the surface roughness and electrostatic charge of electrospun NFs. The PAN/ZnO composite filter with 12 wt%-ZnO showed a filtration efficiency of 98.8% and a pressure drop of 48 Pa for 300 nm aerosol particles, resulting in a quality factor of 0.092 Pa⁻¹. In addition, PAN/ZnO composite exhibited excellent photocatalytic activity in methylene blue (MB) decomposition at 100 and 70.2% efficiencies, respectively, under UV and visible light.     

A Study of Zn-Ca Nanocomposites and Their Antibacterial Properties

This study aimed to develop Ca²⁺ doped ZnO nanoparticles (NPs) and investigate their antibacterial properties against microorganisms of dental interest. Zn-Ca NPs were synthesized by the sol-gel method with different concentrations of Ca²⁺ (1, 3, and 5 wt. %) and subsequently characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-vis spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The Kirby–Bauer method was used to measure antibacterial effects. NPs showed the wurzite phase of ZnO and bandgap energies (Eg) from 2.99 to 3.04 eV. SEM analysis showed an average particle size of 80 to 160 nm. The treatments that presented the best antibacterial activity were Zn-Ca 3% and Zn-Ca 5%. ZnO NPs represent an alternative to generate and improve materials with antibacterial capacity for dental applications.     

Starch-Coated Magnetic Iron Oxide Nanoparticles for Affinity Purification of Recombinant Proteins

Starch-coated magnetic iron oxide nanoparticles have been synthesized by a simple, fast, and cost-effective co-precipitation method with cornstarch as a stabilizing agent. The structural and magnetic characteristics of the synthesized material have been studied by transmission electron microscopy, Mössbauer spectroscopy, and vibrating sample magnetometry. The nature of bonds between ferrihydrite nanoparticles and a starch shell has been examined by Fourier transform infrared spectroscopy. The data on the magnetic response of the prepared composite particles have been obtained by magnetic measurements. The determined magnetic characteristics make the synthesized material a good candidate for use in magnetic separation. Starch-coated magnetic iron oxide nanoparticles have been tested as an affinity sorbent for one-step purification of several recombinant proteins (cardiac troponin I, survivin, and melanoma inhibitory activity protein) bearing the maltose-binding protein as an auxiliary fragment. It has been shown that, due to the highly specific binding of this fragment to the starch shell, the target fusion protein is selectively immobilized on magnetic nanoparticles and eluted with the maltose solution. The excellent efficiency of column-free purification, high binding capacity of the sorbent (100–500 µg of a recombinant protein per milligram of starch-coated magnetic iron oxide nanoparticles), and reusability of the obtained material have been demonstrated.     

Non-Covalent Synthesis of Metal Oxide Nanoparticle–Heparin Hybrid Systems: A New Approach to Bioactive Nanoparticles

Heparin has been conjugated to Fe₃O₄, Co₃O₄, and NiO nanoparticles (NPs) through electrostatic interactions, producing colloidal suspensions of hybrid metal oxide heparin NPs that are stable in water. Negative zeta potentials and retention of heparin’s ability to capture toluidine blue indicate that heparin’s negative charges are exposed on the surface of the coated NPs. IR results confirmed the formation of nanohybrids as did NMR experiments, which were also interpreted on the basis of toluidine blue tests. Transmission electron microscopy results revealed that the heparin coating does not modify the shape or dimension of the NPs. Dynamic light scattering and negative zeta potential measurements confirmed that heparin surface functionalisation is an effective strategy to prevent NP aggregation.